Dual inlet and outlet muffler



June 18, 1968 J. MARTOIA DUAL INLET AND OUTLET MUFFLER Filed Aug. 4, 1966 F0224 Z Wizbz'a United States Patent 3,388,769 DUAL INLET AND OUTLET-MUFFLER Ronald J. Martoia, Jackson, Mich., assignor to Walker Manufacturing Company, Racine, Wis., a corporation of Delaware Filed Aug. 4, 1966, Ser. No. 570,228 12 Claims. (Cl. 18156) This invention relates to exhaust mutilers for internal combustion engines and particularly to mufliers of the type having two inlets and two outlets.

'In dual inlet-dual outlet mufilers, one of the problems confronting the designer is to obtain a balanced arrangement of silencing means so that one of the outlets is not louder than the other, and another problem is to avoid excessive back pressure and short circ-uiting of the gases.

Accordingly, it is an object of the present invention to provide a compact dual inlet-dual outlet mufiier which has an acoustically and pressure balanced design and low back pressure.

A preferred form of the invention is illustrated in the drawings, in which:

FIGURE 1 is a longitudinal cross section through a mufiler embodying the invention;

FIGURE 2 is an end elevation taken from the left of FIGURE 1;

FIGURE 3 is a side elevation taken from the right of FIGURE 1; and

FIGURE 4 is a cross section along the line 44 of FIGURE 1.

The mufiler 1 has a tubular oval shaped shell 3 which is closed at opposite ends by the headers 5 and 7 that are connected to the ends of the shell in interlocked joints 9, as is common practice in the exhaust mufiler field. Around the outside of the shell 3 may be placed an insulating assembly of asbestos and outer sheet metal Wrap 11. Inside of the shell 3 are a series of transverse partitions 13, 15, 17, and 19 which have peripheral flanges that are spot welded to the inside of the shell 3, the spot Welds being indicated throughout by the small x. The partitions divide the inside of the casing 3 into a series of longitudinally separated chambers 21, 23, 25, 27, and 29.

axially aligned, substantially identical inlet tubes 31 and 33; and gas flow out of the mufiier is provided by a pair of aligned substantially identical outlet tubes 35 and 37. Inlet bushings 3'9 and 41 are supported in flanged openings 43 and 45 in the headers 5 and 7 and in turn support the inlet ends of the inlet tubes 31 and 33. Similarly, outlet bushings 47 and 49 are supported in flanged necks 51 Gas flow into the muffler 1 is provided for by a pair of and 53 in the headers 5 and 7 and in turn support the outlet ends of the outlet tubes 35 and 37. The inlet tubes extend through and are supported in and spot welded to flanged necks 55 and 57 in the partitions 13 and 19, re-

spectively. The outlet tubes 35 and 37 extend through and are supported in and spot welded to the flanged necks 59 and 61 in the partitions 15 and 17, respectively. The outlet tubes 35 and 37 also extend through flanged openings 63 and 65 in the partitions 13 and 19 which are somewhat larger in size than the outer diameter of the tubes 35 and 37 so that there can 'be a limited amount of communication between thechambers 21 and 23 and chambers 27 and 29 through their respective openings 63 and 65.

The inlet tube 31 has a louvered section 67 that opens into the chamber 21 and the inlet tube 33 has a similar louvered section 71 that opens into the chamber 29. The outlet tube 35 has a relatively long louvered section 73 which extends through the opening 63 and opens into both chambers 21 and 23. Similarly, the outlet tube 37 3,388,769 Patented June 18, 1968 ice has a relatively long louvered section 75 that extends through the opening 65 and opens into boththe cham- "hers 27 and 29. The louvered sections referred to preferably extend entirely around the tubes. In place of louvers the tubes may be provided with small perforations to provide the acoustic and fluid connection between the inside of the tubes and the respective chambers, though louvers are preferred since they provide better silencing. Supported in and spotwelded to a flanged neck 77 in the partition 15 is a relatively short imperforate tube 79 which overlaps slightly the outlet end of the inlet tube 31. Aligned with the tube 79 but spaced from it, is a similar tube 81 which is supported in and spot welded to a flange neck 83 in the partition 17 and its inlet end overlaps slightly the outlet end of the inlet tube 33. i

The partition 13 has a pierced hole 85 which is slightly larger than the tube 79 and aligned with it; and similarly, the partition 19 has a pierced hole 87 and is slightly larger than tube 81 and aligned with it.

In operation, gas enters the inlet bushings 39 and 41 and passes along the tubes 31 and 33 to leave them and enter the inlet chambers 23 and 27. The main body of gas then reverses flow slightly to flow outwardly and then inwardly into the tubes 79 and '81 from which it flows into the central outlet chamber 25. Gas in the outlet chamber then reverses flow to enter the projecting inlet ends of the outlet tubes 35 and 37 through which they flow to the outlet bushings 47 and 49. Obviously, the inlet bushings 39 and 41 and the outletrbushings 47 and 49 are suitably clamped to exhaust pipes and tailpipes, respectively.

The irregular path that the main body of gas follows in flowing through the tubes just described, extracts energy and sound from the gas as it passes from the inlet to the outlet of the mufller, The action of the chambers surrounding the various louvered sections of the tubes at tenuates medium to the high frequency sounds in the gases. The imperforate tubes 79 and 31 acting in con junction with the chambers 21 and 23 and the chambers 27 and 29 respectively, and the openings 85 and 87 produce a modified type of compound resonator action which attenuates the relatively low frequency sounds in the gases.

It is apparent that the flow of the main body of gases entering from the two sides of the muffler is balanced since the construction in each half of the muflier is substantially identical. The flow of the main body of gases is also relatively unrestricted and this tends to minimize back pressure. Additionally, as a means to minimize back pressure, it will be noted that there is a possibility of substantial cross bleeding from the louvered sections of tubes 31 and 33 through chambers 21 and 29 to the louver sections of tubes 35 and 37. Additionally, cross bleeding can occur by flow directly from chambers 23 and 27 into the louver sections of tubes 35 and 37.

It will be noted that the various tubes project a substantial distance into the respective chambers in which they terminate. This enables the overall length of the unit to be substantially shortened and at the same time this arrangement also has a tendency to improve the silencing effect since the space behind the projecting portions of each tube tends to act somewhat as a dead gas space with respect to the gas flowing out of the tube and therefore to absorb some of the acoustic vibrations emanating from or entering the respective tubes.

Modifications may be made in the structure shown without departing from the spirit and scope of the invention.

I claim:

1. A dual inlet-dual outlet muffler for silencing exhaust gases or the like comprising an elongated tubular housing, partition means in the housing defining a central outlet chamber and a pair of inlet chambers one located on each side of the outlet chamber, a pair of inlet tubes supported in the housing and emptying respectively into said inlet chambers, a pair of outlet tubes supported in the hosuing and opening into said outlet chamber, gas passage means connecting said inlet chambers to said outlet chambers, said partition means forming an additional pair of silencing chambers in said housing one located on each side of the outlet chamber, and means acoustically connecting said silencing chambers with gas flowing through the muffler.

2. A mufiler as set forth in claim 1 wherein said inlet chambers are located next to said outlet chamber,

3. A mufller as set forth in claim 2 wherein said gas passage means comprises conduits extending into both the inlet and outlet chambers.

4. A muffler as set forth in claim 3 wherein said conduits are imperforate.

5. A mufiler as set forth in claim 4 wherein said inlet tubes extend into said inlet chambers and overlap said conduits.

6. A mufiler as set forth in claim 4 wherein said outlet tubes extend into said outlet chamber and overlap said conduits.

-7. A muffier as set forth in claim 4 wherein said inlet tubes extend into said inlet chambers and overlap said conduits and said outlet tubes extend into said outlet chamber and overlap said conduits.

8. A muifier as set forth in claim 2 wherein said tubes extend through said silencing chambers and at least one is perforated in each chamber.

9. A mufiler as set forth in claim 8 wherein all said tubes are perforated in said silencing chambers.

10. A muffier as set forth in claim 9 wherein said partition means has openings therein connecting said inlet chambers to said silencing chambers.

11. A mufller as set forth in claim 10 wherein said gas passage means comprises conduits extending into both said inlet and outlet chambers and aligned with said openings.

12. A mufiler as set forth in claim 1 wherein said outlet tubes extend through said inlet chambers and are perforated therein.

References Cited UNITED STATES PATENTS 2,078,420 4/ 1937 Sheldrick.

2,337,299 12/ 1943 Noblitt et al. 181-54 2,361,133 10/ 1944 Sprouse.

3,232,374 2/1966 Powers 181-54 XR FOREIGN PATENTS 1,056,421 4/ 1959 Germany.

ROBERT S. WARD, 112., Primary Examiner. 

1. A DUAL INLET-DUAL OUTLET MUFFLER FOR SILENCING EXHAUST GASES OR THE LIKE COMPRISING AN ELONGATED TUBULAR HOUSING, PARTITION MEANS IN THE HOUSING DEFINING A CENTRAL OUTLET CHAMBER AND A PAIR OF INLET CHAMBERS ONE LOCATED ON EACH SIDE OF THE OUTLET CHAMBER, A PAIR OF INLET TUBE SUPPORTED IN THE HOUSING AND EMPTYING RESPECTIVELY INTO SAID INLET CHAMBERS, A PAIR OF OUTLET TUBES SUPPORTED IN THE HOUSING AND OPENING INTO SAID OUTLET CHAMBER, GAS PASSAGE MEANS CONNECTING SAID INLET CHAMBERS TO SAID OUTLET CHAMBER, SAID PARTITION MEANS FORMING AN ADDITIONAL PAIR OF SILENCING CHAMBERS IN SAID HOUSING ONE LOCATED ON EACH SIDE OF THE OUTLET CHAMBER AND MEANS ACOUSTICALLY CONNECTING SAID SILENCING CHAMBERS WITH GAS FLOWING THROUGH THE MUFFLER. 